Yeodongsaengirang Bimil Lesson

"I heard you're the master at sex."
His friends call him Dr. Sex, but in reality, Jin-Yeong is still a virgin. However, he lies to his sister, Bom, and acts like he has experience. However... He didn't expect Bom to sneak into his room asking him to teach her about sex every night!!!
(Source: DAYcomics)